Removable plug for drilling strings



Sept. 1, 1942.

` H. -V. ySTEADMAN E'lAL REMOVABLE PLUG FOR DRILLING STRINGS ssheets-sheet 1 Filed J'une 24, 1941 Figl l Ems E. Davs Bg #har A HornzqSept. l, 1942.

Filed June 24, 1941 Fig. lIl

H. v. STEADMAN 1-:r` AL y REMovABLE' PLUG" FOR4 DRILLING STRINGS sSheets-sheet 2 2m www 3-O IH H mul 3o FQJY inventors: Hor-cz VivianSizadrnnn Ellis E. Davis,

Patentedfept. l, 1942 REMOVBLE PLUG FOR DRILLING STRINGS Horace VivianSteadman and Ellis E. Davis, Tulsa, Okla., assignors to ShellDevelopment Com-v pany, San f Francisco, Calif., `a corporation ofDelaware Application June 24,'1941, serial No. .399,476

11 Claims. (ci. g55-72) The present invention relates to the drillingyof wells and pertains more particularly to drill string plugs or seals,which may be suitably placed in and removed from the drill stringwithout the necessity of removing or raising the drilling equipment fromthe borehole.

In drilling wells by the rotary method, it is essential 4that a highascending velocity of the drilling mud be maintained in order to removethe drill cuttings from the well. A high ascending mud velocity becomesincreasingly important when the drill is making hole more rapidly, whenthe'cuttings become larger or denser, and especially when effecting theso-called well-cleaning operations preparatory to completing the well.For the purpose ofY increasing the ascending velocity of the mud fluidwithout overtaxing `the pumping equipment, it is generally the practiceto apply reverse circulation, whereby the mud. iluid is pumped down theannular lspace between the drill string and'the casing or borehole andthen passes up through the drill string. Due to the smaller space withinthe drill string the fluid passes upwards 'at a greater rate, therebyincreasing the fluid carrying power for cuttings.

When employing this method of mud circulation, it is, usually necessaryto enlarge the Water courses through the drill bit.

As mentioned above, it is'generally desirable to wash the wa11s-of thesection of the borehole l" when this section of the bore-hole is thoughtto be` the producing zone, and it is expected to complete the well'andtoput it on production. Heretofore, the washingwas accomplishedv byreplacing the drill 'bit having enlarged water courses f with a plug orthe like having small lateral jetting holes and then pumping thecirculation medium down through the 'drill string and out through thejetting holes while rising and 'lowering the drill string to subject allor normally tion to provide means for eliminating the necessity ofremoving the drill string from the borehole while jet-washing the wallsand removing the detritus accumulated after each washing.

It is another object to provide drill string plugging means insertableinto and removable from said drill string by uid circulation throughsaid string and v,capable of closing oil the watercourses through thedrill bit while permitting iluid now from the drill string out-throughjetting holes positioned arelatively short distance above the drill bit.Y It` is a further object to provide a simple, inexpensive, andeflicient well drill string plugging f device, which may be passed downthe drill string to the desired position by means of fluid circulation.It is still another object to provide means for lowering and raisingvarious tools in a string of invention has particular relation tocertain novel ony a part of the borehole to thel jetting action. v

The detritus, which accumulates in the bottom of the borehole duringjetting, is then 'removed by reverse circulation after reinstallingtheirill bit. Frequently, and particularly after shooting a well withexplosives, it is desirable to wash a section of the borehole severaltimes and to remove the detritus washed down on the completion of eachv4letting. Since each change to replace the drill bit with the jettingtool or vice versa requires withdrawing the entire drill string from thehole, the procedure of jet-washing the borehole l and removing thedetritus several times is a timeconsuming and therefore costlyoperation.

It is, therefore, an object of the present invenfeatures ofconstruction, operation, and-arrangement of parts, an example of whichis given in this specification 'and illustration in the accompanyingdrawings, wherein: Y

FigureI is a view. partly in section, of a preferred embodiment of thepresent device as positionedY in a well drill string;

Figure II is a view similar to that of Figure I, showing the collapsedposition of the present device in a well drill string during jet-washingof the borehole walls;

Figure III is a view similar tovthat of Figures I and II, showing thepositionof the device just as flow is reversed to remove the device fromthe well drill string; i

Figure IV is an enlarged longitudinal cross-sectional view of thepresent device; y a

Figure V is an elevation of the present device as attached to a casingspear for plugging the' lower end of a drill string; and

Figure VI is a view, partly in elevation, showing the use of the presentinvention in combination with instruments for taking well cores.

Referring to Figure IV of the drawings, a preferred embodiment of theplugging device comprises a mandrel or stem I having threaded ends2"and' 3, a lower hydraulic cup 5 coaxially and rigidly attachedadjacentpne end of said mandrelk I, and an upper hydraulic cup 6vcoaxially and slidably mounted on said mandrel I.- The cups 5 and 6 maybe single, as shown, or mul- 2 tiple units and are adapted to withstandthe fluid pressure imposed upon them. The lower hydraulic cup isupwardly flared; that is, it has a concave upper face 1, allowingpressure applied thereabove to expand it. The upper cup 5 has a concavelower face 5, opposing the face 1 of the lower cup 5. The cups maybe ofany suitable design, and are made of -elastic or exible material suchas, preferably, natural or synthetic rubber, or other suitablematerials, for example, can-l vas, rubberized canvas, etc. The cups 5and 5 are preferablyreinforced by protective metal rings Il within theaxial bores II of said cups, and by a plurality of wires I2 attached atone end to said ,rings III and passing therefrom to and along orposition. The cups 5 and 5 may be further rein-k forced by means ofannular 4thimbles -or rings having tapered faces 2I `complementing andabutting the convex faces of said cups.

The lower cup 5 is rigidly held in place on the lower end of the mandrelI by means of a plug nut 25 screwed onto the threaded end 5 of themandrel and abutting the annular thimble 2l on one side of the cup 5 andby means of a tubular follower v25 abutting the cup 5 and reinforcingring I0 on the other side of the cup 5. The

plug nut 25 is suitably prevented from loosening by means of,fonexample, lock screws 30. Simi- -lar lock screws 5I or the likeprevent movement of the tubular follower 25.

A nut 35 and lock nut 36 are screwed onto the other threaded end 2 ofthe mandrel I and constitute stop means against which the movable 4 cup5 is preferably normally held by suitable resilient means, such as acoil spring 4|! surrounding the mandrel and acting between thestationary tubular follower 28 and a slidable tubular foltions for whichthe present device is adapted, the

l spring 45 or other resilient means is not absolutely necessary.When/the resilient means is omitted as for some purposes, it ispreferable that some suitable spacer means be provided between the cupsto stop movement of said slidable cup i toward the fixed cup 5 at apredetermined distance away from said fixed cup so that'the cups will beprevented from coming together in such a way as to prevent fluid fromacting against. the concave facesf of the cups to expand them. In thepreferred embodiment described above, the followers 26 and 4I, whichproject out fromthe concave faces of the cups', readily serve as stopmeans for this purpose. If desired, both cups 5 and 6 mayrbe xedlyattached adjacent the respective ends of the mandrel I; however, formost purposes, greater efficiency and-facility of action -of the deviceis obtained when some auch resil- .ient means is provided.

l lower 4I similar to follower 25. For some operai vin connection withjet-,washing the borehole and depending thereinto a drill pipe'string5I, to the lower end of which is attached a drill bit 53 having a watercourse or courses 54 passing therethrough. The lower section of thedrill pipe string 5I is provided with lateral jetting holes 55 at arelatively short distance above the lower end of said string, and,preferably, with a non-nowrestricting stop means, such as a pin 51bridging the bore of the string closely adjacent the lower end thereof.If desired, a special tube or pipe containing the ietting holes 55andthe stop pin 51 may be inserted between the lower end of the drillstring 5I and drill bit 53. Likewise. the shank of the drill bit 53 mayserve as stop means A instead of any special means, if desired.

When it is desired to jet-washv the walls of the borehole after drillingwith reverse circulation, the path of the circulationmedium is directedso that the nuid passes in the regular manner down through the drillstring 5I out through the water courses 54 in the drill bit and up tothe surface' through the annular space between the drill string 5I andthe walls of the borehole 50.

l Ihepresent plugging device is then introduced into the'drill stringand is forced down within the drill string by the pressure ofthecirculation medium above it acting upon the lower and statlonaryhydraulic cup 5, which is expanded against the walls of the drill stringby said pressure, as shown in Figure I. The plugging device travels down,through the drill string until the plug nut 25 on the lower endcontacts the stop pin 51. At this point in the procedure, the spring 4lis still expanded and the upper cup 8 is positioned above the jettingholes or ports 55, as

shown in Flggure I. With a further increase in pressure of thercirculation medium occurring when the device is stopped by the pin 51,the upper slidable cup I is forced downwards against the action of thespring 40,' thereby exposing the jetting ports 55 to the full 'force ofthe pressure of the circulation medium, as shown in Figure 1I. With thevwater courses 54 in the -drill bit closed by the expanded lower cup 5and with the jetting ports I5 exposed, the circulation medium flows at ahigh rate out through the small jetting ports" ycup 5 expands intosealing engagement with the drill string walls. On continued ow ofcirculation medium. through the water courses 54 and thejetting ports 55into the drill string 5I below the cup 5 the plugging device travelsup-kr ward to the-surface of well, where it inay be removed from thedrill string. Reverse circulation may then be continued to" remove thedetritus which hasiaccumulated inthe bottom of the borehole during thejet-washing.

Y tion of the above-described device. when used '75 Drilling maythen ,beresumed. or by again insetting and removing the plugging device theborehole -walls 'may be jet-washed and the detritus removed any numberof times before resuming drilling without at any time having to removethe drill'pipe string yfrom the borehole. It may be i'eadily seen thataccording to the present invention the considerable time necessary forremoving and replacing the drill string after and before each operationis obviated. Further, the present plugging device may be used incombination with various well tools for positioning said tools in adrill pipe string or tubing string and for removing'said toolsthereffrom. Referring to Figure V,- one highly advantageous combinationiswith a casing spear or similar inside gripping means. In the eventthat the formation pressures become suicient to displace the fluid'frornthe well, thereby causing a disastrous situation commonly known asa blowout, it becomesfnecessary to plug the drilling string in order to avoidhazard to the well, personnel, and farm land. To prevent such anoccurrence, there may be inserted into the drill string and forceddownward therethrough the combination of the plugging device of thepresent invention with means for grippingthe walls of the drill string,which means move into wall-grip 25 barrel. The lower end of the corebarrel 90 is ping engagement upon'I upward movement thereof. For thispurpose, the plugging device may be inverted, as shown, and the plug nut25 replaced by any suitable inside wall-gripping means, such as, forexample, a casing spear generally designated as 10. The spear 10 may,for example, comprise a mandrel 1| having lateral recesses 1.2 providedwith downwardly diverging tapered faces 13, as shown in Figure V.Tapered slips 14 having horizontal teeth 15 on their outer commonlyknown as a pack-off rubber," aids in effecting a stronger seal againstthe high pressure differential across the plugging device. By means 5 ofthis combination of the plugging device with a casing spear, the drillstring can be removed from a flowing well while maintaining said wellunder control. l

As a further example of one of the many uses l o i' the presentinvention, theplugging device may be used in connection with meansforobtaining cores from a well. With the present device a core b arrel maybe removed from the weil, the cores emptied from the core barrel, andthe core barrel l reinserted into core-taking position without re- 2 0of the plugging device by means of a coupling 9| containing', ifdesired, an upwardly-opening ball valve 92 or .the like, which providesa one-way passage for fluid flow from the inside of the core barrel 90to the annular 'space outside the core taking, as shown in Figure VI,the tapered face 93 on the lower end of the core barrel 90 seats in acomplementary tapered internal shoulder 96 of the core bit head 91.,which is provided withA water courses 98 to allow circulation ofdrilling iiuid vertical sides are adapted to slide downwardlytherethrough. The bit head 91 is attached to and outwardly on thetapered faces 13 intov Wall-gripping engagement upon upward movement ofthe mandrel 1|. Said slips 14 are held in slidable engagement with saidtapered faces 13 by means of engagement of a key 16 and key way on eachface 13 and slip 14, respectively, as shown in Figure V, or vice versa.It is often advisable when so using 'the plugging device to substitute,asshown in Figure V, a tubular mem-l ber 18 of rubber or like vmaterialfor the sp1-ing A40 to assist the upper cup in sealing ofi the drillstring as described below. If desired, instead of gripping meansattached above, as shown, or below the plugging device, as justdescribed, Aa dog- 'mechanism or the like may be carried between forcesthe combination assembly down to the de` sired position. By metering theamount of uid introduced into the drill string after the device isinserted, the position of the device is accurately known. 'When the'device reaches the desired l position, the pressure on the fluid abovethe device is released, allowing the full well pressure to act againstthe cup 5. The cup 5 is thereby expanded into sealing engagement withthe walls of the drill string and caused to move slightly upward. Theupward movement of the mandrel 1| carried by the plugging device causesthe toothed slips 1I to be moved outwardly along the tapered faces 13 ofthe recesses 12 into engagement with the walls of the drill string. Theplugging device is thus held in the |desired position within the drillstring and thesealing action of the cup 5 prevents upward ow of wellfluid through the drill string, thereby bringing the ,wellunder-control.

the lower end of a tubular member |00, which is in turn attached to thelower end of the drill string 5|. The tubular member 00 has a thickenedportion |02 disposed so that, when the assembly of the plugging deviceand the core barrel is properly vpositioned for core taking, the lowercup 5 is within the thickened portion |02. The

thickened portion |02 is cut away to form vertical slots |03 allowing[fluid to by-pass the lower sition, as shown inv Figure VI, drillingiiuid is circulated down through the drill string 5| past 5 the uppercup 6 and through the slots |00 in the ,thickened portion |02 of thetubular member |00 past the lower cupi vand thence down through theannular space` |0| between the corebarrel 90 and the tubular member |00and out through 55 the watercourses 98 in the core bit head 91 into the.borehole and up through the annular space between the tubular member|00 or drill string 5|J and the bore hole 50. The pressure againsty thelower cup 5 of the fluid passing downpast it holds the core barrel 90 inseated position in Coring proceeds with fluid circulation in this manneruntil the core taken the drill bit head 91.

,lls the core barrel v90. I' 'I'he core barrel 90 containing aV coreheld therein by means of catchers 95 and the plugging device attachedthereaboveY` is then removed from the-tubular member |00l and drillstring 5| by reversing the direction of fluid circulation. In additionto the imposition of fluid pressure against'the lower extremiiyof 7 thecore barrel, the pressure of the fluid passing 5- the surface by ymeansof iluid circulation.

The tubular member 10, such as a rubber sleevev After removing the corebarrel from the well and emptying the core therefrom, the assembly maybe reinserted into the drill string and forced down through drill string5I by yfluid pressure thereabove into position for taking another core.

Thus, it may be readily seen that. the use of the plugging device incombination with a core barrel oers the outstanding advantage of tak.ing an unlimited number of well cores without removing the drill stringfrom the borehole after coring is started, thereby effecting aconsiderable saving of time and expense.

' It will be readily understood that thel drawings and description areillustrative onlyv of preferred embodiments of the present invention andthat various modifications may be readily made without departing fromthe scope of the inventiom'.

as defined in the appended claims. Thus, for example, the pluggingdevice may be used to advantage in combination with various tools otherpand against the walls of the well pipe when uid flow is directedagainst their concave sides.

6. A well pipe tool adapted to pass to and from a desired position in awell pipe by fluid flow through said pipe, said tool comprising amandrel, a hydraulic cup rigidly fixed coaxially on said mandreladjacent one end thereof and having its concave side facing toward theother end than those indicated and, likewise, modifications Y may bemade in the plugging device itself.

We claim as our invention: 1. A well pipe tool adapted to be movedwithin va well pipe by uid circulation, said tool comprisinga mandrel,and two opposed hydraulic,

adapted for limited slidable motion on said mandrel.

2. A well pipe tool adapted to be moved within a well pipe by fluidcirculation, said tool comprising a mandrel and two hydraulic cupscoaxially mounted on said mandrel and having their concave facesdirected toward each other, one of said cups being rigidly fixed on saidmandrel adjacent one end thereof, and the other cup being adapted forlimited slidable motion on said mandrel.

3. A well pipe tool adapted to pass to and from a desired position in awell pipe by fluid flow through said pipe, said tool comprising amandrel; a hydraulic cup` rigidly fixed coaxially on said mandreladjacent one end thereof and of the mandrel, a second hydraulic cupslidably and coaxiallyi attached to said mandrel, the concave side ofsaid second cup facing the concave side of said fixed cup, and resilientspacer means adapted to hold said slidable cup normally at apredetermined distance from said fixed cup.

'7. A well pipe tool adapted to pass to and from va desired position ina well pipe by fluid flow through said pipe, said tool comprising amandrel, a hydraulic cup rigidly xed coaxially on said mandrel adjacentone end thereof and having its concave side facing toward the other endof the mandrel, a second hydraulic cup slidably and coaxially attachedto said mandrel, thef concave side of said second cup facing the concaveside of said' fixed cup, and resilient spacer means disposed betweensaid cups and adapted to hold said slidable cup normally at apredetermined distance from said fixed cup.

8. A pressure shut-oil' device for well pipe strings, said devicecomprising a mandrel provided with gripping means adapted to engage theinternal walls of said pipe upon upward movement of saidv mandrel, meansto position said device within saidpipe by a downward fluid now, saidmeans comprising an upwardly ilaring hydraulic cup coaxially carried bysaid mandrel, and means for engaging said gripping means with the pipewalls by `a reversal of said fluid flow, said means comprising adownwardly aring hydraulic cupcoaxially carried by said mandrel.

9. A pressure shut-off device for well pipe strings, said devicecomprising a mandrel prohaving its concave side facing toward the otherend `of the mandrel, and a second hydraulic cup coaxially attached tosaid .mandrel and adapted for limited slidable motion thereon, theconcave side of said second cup facing'the vconcave side of said fixedcup.

4. A well pipe tool adapted to pass to and from a -desired position ina' well pipe by uid flow through said pipe, said tool comprising amandrel, a hydrauliccup rigidly fixed coaxially on said mandrel adjacentone end thereof and having its concave side facing toward the othermandrel,'a hydraulic cup rigidly fixed coaxially on said mandreladjacent one end thereof and having its concave side facing toward theother end of the mandrel, and a second hydraulic cup coaxiallyattached'to said mandrel and adapted for limited slidable motionthereon; the concave side of said second cup Afacing the concave side tof said gated cup, said cups being adapted to exsaid barrel coaxiallytherewith, and means for vided with gripping means adapted to engage theinternal walls of said pipe upon upward vmovement of said mandrel, meansto position said device within said pipe by a downward uid flow, saidmeans comprising an upwardly flaring hydraulic cup coaxially carried bysaid mandrel, means for engaging said grippingfmeans with the pipe wallsby a reversal of said uid'flow,

said means comprising a downwardly flaring hydraulic cup coaxiallycarried by said mandrel,

one of said cups being fixedly attached to said mandrel and the otherbeing adapted for limited slidable motion thereon, and aresilient-spacer sleeve lcoaxially carried by said mandrel between saidhydraulic cups, said sleeve being adapted to be deformed into contactwith the pipe walls by a motion of saidl movable cup toward said fixedcup.

10. For'use in coring operations in combination with a drill stringhaving a core bit and an v internal axially segmented restriction abovesaid bit, a coring tool comprising a core barrel adapted to seat withinsaid bit, a mandrel, valved means for rigidly afllxing said mandrelabove seating said barrel within said bit and for removing it 4therefromby fluid circulation, said means comprising an upwardly flaringhydraulic i cup coaxially carried by said mandrel and adapted toregister with said segmented restriction in the drill string when thecore barrel is seated within the bit, a downwardly flaring hydraulic cupcoaxially carried by said mandrel above said first cup, one of said-cupsbeing xedly attached tothe mandrel and the other 'adapted for limitedaxial motion thereon, and resilientV spacer means for normallymaintaining said cups at a small la'teral jet ports in its lower portionadjacentsaid bit, a mandrel having at its lower end an upwardly flaring'hydraulic cup fixedly attached thereto and at its upper end a down-`wardly ilaring hydraulic cup axially-'slidable on said mandreltowardssaid ilxed cup, resilient means spacing said cups on saidmandrel, said mandrel being adapted to be pumped .down the drill stringby liquid circulation, stop means for arresting said mandrel adjacentthe drill bit,

whereby said lower'cup is caused to close the bit opening and said uppercup is maintained above said lateral ports, means for slidingly forcingsaid upper cup on said mandrel to a position below said ports byapplying hydraulic pressure within the drill pipe, and means to removesaid mandrel to the surface by reversingthe direction of the liquidcirculation.

HoRACE VIWANV STEADMAN. ELLIS E. Davis.

